1. Field of the Invention
The present invention relates to a wireless IC device and a manufacturing method thereof. More specifically, the present invention relates to a wireless IC device, such as a non-contact wireless IC medium or a non-contact wireless IC tag, for example, used in an RFID (radio frequency identification) system, and a manufacturing method thereof
2. Description of the Related Art
Wireless IC devices including a module in which a wireless IC chip is mounted on a substrate and a radiation plate have been developed. In such a wireless IC device, a recess is provided in the substrate and the wireless IC chip is mounted in the recess.
Japanese Unexamined Patent Application Publication No. 2004-319848 discloses a semiconductor apparatus manufactured by forming a wiring substrate by bonding copper bumps 116a and 118a and wiring patterns 117 and 119 to both surfaces of a resin substrate 110 with prepregs 120 therebetween as shown in a sectional view in FIG. 12A, counterboring a predetermined location of the wiring substrate so as to form a recess 122 as shown in a sectional view in FIG. 12B, electrically connecting a semiconductor chip 130 to an edge surface A of the copper bump 116b exposed on the bottom surface of the recess 122 as shown in a sectional view in FIG. 12C so as to mount the semiconductor chip 130 in the recess 122, and then filling the recess 122 with a resin 124 so as to seal the semiconductor chip 130.
If a multilayer resin substrate is formed and then subjected to counterboring, which is a mechanical process, as described in Japanese Unexamined Patent Application Publication No. 2004-319848, the number of steps is increased and a counterboring apparatus is required. Thus, the manufacturing cost is increased.
In addition, since a first main surface of the resin substrate having the recess and a semiconductor chip are connected, it is difficult to provide wiring on the inner circumferential surface of the recess formed by counterboring. This makes it difficult to provide wiring having the shortest possible length and wiring must be routed such that the length thereof is increased. For example, wiring must be routed from the bottom surface of the recess 122 to a wiring pattern 117 on a second main surface of the multilayer resin substrate via the copper bump 116b and from the wiring pattern 117 on the second main surface to the first main surface via the copper bumps 116a and 118a. 
When the wiring is routed as described above, an unnecessary inductor component or capacitor component occurs in a portion of the wiring. This degrades the electrical properties and/or complicates the manufacturing process, thereby causing reduced yield, for example. This disadvantageously increases the manufacturing cost.